Method and apparatus for implementing transmission diversity using single transmitter

ABSTRACT

A method and an apparatus for implementing transmission diversity using a single transmitter in a wireless communication system are provided. The method of operating a transmitter for transmission diversity in a wireless communication system includes generating a first data symbol by receiving a baseband signal from a data source, generating a second data symbol having an equal phase to the first data symbol, generating a first complex conjugate symbol by performing a complex conjugate operation for the first data symbol, generating a second complex conjugate symbol having a phase difference of 180 degrees from the first complex conjugate symbol, transmitting the first data symbol through a first transmission antenna and transmitting the second data symbol through a second transmission antenna in a first time slot, and transmitting the first complex conjugate symbol through the first transmission antenna and transmitting the second complex conjugate symbol through the second transmission antenna in a second time slot.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. §119(a) of a Korean patent application number 10-2019-0105357, filed onAug. 27, 2019, in the Korean Intellectual Property Office, and of aKorean patent application number 10-2020-0084265, filed on Jul. 8, 2020,in the Korean Intellectual Property Office, the disclosure of each ofwhich is incorporated by reference herein its entirety.

BACKGROUND 1. Field

The disclosure relates to a method and an apparatus for implementingtransmission diversity using a single transmitter in a wirelesscommunication system.

2. Description of Related Art

In a mobile communication environment, a sum of multi-path signalshaving different amplitudes and phases is received, and thus a qualityof a received signal may be significantly reduced due to multi-pathfading.

Accordingly, various diversity schemes have been researched to improve acommunication quality, and particularly much research on a transmissiondiversity scheme in a downlink (DL) from a base station to a terminalhas been conducted.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea method and an apparatus for implementing transmission diversity usinga single transmitter, a single processor for processing a basebandsignal, and a phase adjustment coupler.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a method of operating atransmitter for transmission diversity in a wireless communicationsystem is provided. The method includes generating a first data symbolby receiving a baseband signal from a data source, generating a seconddata symbol having an equal phase to the first data symbol, generating afirst complex conjugate symbol by performing a complex conjugateoperation for the first data symbol, generating a second complexconjugate symbol having a phase difference of 180 degrees from the firstcomplex conjugate symbol, transmitting the first data symbol through afirst transmission antenna and transmitting the second data symbolthrough a second transmission antenna in a first time slot, andtransmitting the first complex conjugate symbol through the firsttransmission antenna and transmitting the second complex conjugatesymbol through the second transmission antenna in a second time slot.

In accordance with another aspect of the disclosure, a transmitter fortransmission diversity in a wireless communication system is provided.The transmitter includes a processor, a phase adjustment couplerconnected to the processor to operate and including a switch circuit anda coupler circuit, and a first transmission antenna and a secondtransmission antenna connected to the phase adjustment coupler tooperate, wherein the processor is configured to generate a first datasymbol by receiving a baseband signal from a data source and generate afirst complex conjugate symbol by performing a complex conjugateoperation for the first data symbol, the phase adjustment coupler isconfigured to generate a second data symbol having an equal phase to thefirst data symbol and generate a second complex conjugate symbol havinga phase difference of 180 degrees from the first complex conjugatesymbol, the first data symbol is transmitted through the firsttransmission antenna and the second data symbol is transmitted throughthe second transmission antenna in a first time slot, and the firstcomplex conjugate symbol is transmitted through the first antenna andthe second complex conjugate symbol is transmitted through the secondantenna in a second time slot.

In accordance with another aspect of the disclosure, a method ofoperating a receiver for transmission diversity in a wirelesscommunication system is provided. The method includes receiving a firstdata symbol and a second data symbol in a first time slot, receiving afirst complex conjugate symbol and a second complex conjugate symbol ina second time slot, and reconstructing a data symbol to whichtransmission diversity is applied, based on the first data symbol, thesecond data symbol, the first complex conjugate symbol, and the secondcomplex conjugate symbol, wherein the first data symbol and the seconddata symbol have an equal phase, the first complex conjugate symbol andthe second complex conjugate symbol have a phase difference of 180degrees, and the first complex conjugate symbol is generated byperforming a complex conjugate operation for the first data symbol.

The disclosure discloses an apparatus and a method for implementingtransmission diversity only through a single processor for processing abaseband signal.

The disclosure discloses an apparatus and a method for implementingtransmission diversity having small power consumption.

The disclosure has an effect of securing a low Bit Error Rate (BER)while applying transmission diversity in a simple structure.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram of a transmission diversity method accordingto an embodiment of the disclosure;

FIG. 2 is a block diagram of a communication system according to anembodiment of the disclosure;

FIG. 3 is a block diagram of a transmitter according to an embodiment ofthe disclosure;

FIG. 4 illustrates a phase adjustment coupler according to an embodimentof the disclosure;

FIG. 5 is a flowchart illustrating an operation of a transmitter towhich transmission diversity is applied according to an embodiment ofthe disclosure;

FIG. 6 is a flowchart illustrating an operation of a receiver to whichtransmission diversity is applied according to an embodiment of thedisclosure;

FIG. 7 is a graph illustrating comparison of a Bit Error Rate (BER) whentransmission diversity is applied according to an embodiment of thedisclosure;

FIG. 8 is a graph illustrating comparison of a Bit Error Rate (BER) whentransmission diversity is applied according to an embodiment of thedisclosure;

FIG. 9 is a graph illustrating a reflection loss of a phase adjustmentcoupler according to an embodiment of the disclosure;

FIG. 10 is a graph illustrating an insertion loss and an isolationdegree of a phase adjustment coupler according to an embodiment of thedisclosure;

FIG. 11 is a graph illustrating a phase difference between outputsignals of a phase adjustment coupler according to an embodiment of thedisclosure;

FIG. 12 illustrates actual implementation of a coupler circuit accordingto an embodiment of the disclosure; and

FIG. 13 illustrates actual implementation of a coupler circuit accordingto an embodiment of the disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Various embodiments according to the technical idea of the disclosureare provided to more completely explain the technical idea of thedisclosure, and various modifications and changes may be made thereto.The scope of the technical idea of the disclosure is not limited toembodiments set forth below, and these embodiments are rather providedto make the disclosure more complete and perfect and fully transfer thetechnical idea of the disclosure to those skilled in the art.

As used herein, such terms as “a first” and “a second” are used todescribe various members, regions, layers, portions, and/or elements,but it will be apparent that these members, regions, layers, portions,and/or elements are not limited by such terms. Such terms do not meanspecific order, rank, or superiority, and are used only to distinguishone member, region, portion, or element from another. Therefore, in thefollowing description, a first member, region, portion, or element mayrefer to a second member, region, portion, or element without departingfrom the teaching of the technical idea of the disclosure. For example,a first element may be termed a second element, and similarly, a secondelement may be termed a first element without departing from the scopeof the disclosure.

Unless defined otherwise, all terms used herein, including technical andscientific terms, have the same meaning as those commonly understood bya person skilled in the art to which the disclosure pertains. Such termsas those defined in a generally used dictionary may be interpreted tohave the meanings equal to the contextual meanings in the relevant fieldof art, and are not to be interpreted to have ideal or excessivelyformal meanings unless clearly defined in the disclosure.

As used herein, the term “and/or” includes each one of membersenumerated together and all possible combinations of one or more of themembers.

Hereinafter, embodiments of the disclosure will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a transmission diversity methodaccording to an embodiment of the disclosure.

Referring to FIG. 1, when a data symbol transmitted by a firsttransmission antenna (ANT1) is s₀ in a first time slot and s₁in a secondtime slot, the data symbol as shown in Equation 1 may be transmittedthrough the first antenna and a second antenna (ANT1 and ANT2).

According to an embodiment, when the data symbol is transmitted, ordersof the data symbols may be shuffled using a space-time encoder block,and the data symbols may be transformed through a complex conjugate or anegative (−) operation and transmitted by a first antenna and a secondantenna (ANT1 and ANT2).

$\begin{matrix}\begin{bmatrix}s_{0} & s_{1} \\{- s_{1}^{*}} & s_{0}^{*}\end{bmatrix} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Specifically, the first data symbol (s₀) is transmitted through thefirst antenna (ANT1) and −s*₁ that is transformed from the second datasymbol is transmitted through the second antenna (ANT2) during a firsttime slot interval. In a second time slot interval, the sequences areexchanged, and thus s₁ may be transmitted in the first antenna and s*₀may be transmitted in the second antenna.

When the data symbol is received through a third antenna (ANT3), areceived signal y^(k) in a k^(th) time slot may be given as shown inEquation 2 and Equation 3. n^(k) denotes Additive White Gaussian 1Noise(AWGN) in the k^(th) time slot. When a channel characteristic from thefirst antenna (ANT1) to the reception antenna (ANT3) is defined as h¹and a channel characteristic from the second antenna (ANT2) to thereception antenna (ANT3) as h₂, y^(k) may be defined by Equation 2 andEquation 3.y ¹ =h ₀ s ₀ +h ₁(−s* ₁)+n ¹  Equation 2y ² =h* ₀ s* ₁ +h ₁ s* ₀ +n ²  Equation 3

Equation 4 below may be derived through summarization of Equation 2 andEquation 3.

$\begin{matrix}{\begin{bmatrix}y^{1} \\y^{2}\end{bmatrix} = {{\begin{bmatrix}h_{0} & {- h_{1}} \\h_{1}^{*} & h_{0}^{*}\end{bmatrix}\begin{bmatrix}s_{0} \\s_{1}^{*}\end{bmatrix}} + \begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

Equation 4 is summarized using Equation 5 and Equation 6.

$\begin{matrix}{H = {\begin{bmatrix}h_{0} & {- h_{1}} \\h_{1}^{*} & h_{0}^{*}\end{bmatrix}\begin{bmatrix}s_{0} \\s_{1}^{*}\end{bmatrix}}} & {{Equation}\mspace{14mu} 5} \\{H^{+} = {\left( {H^{H}H} \right)^{- 1}H^{H}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

The transmitted data symbol may be estimated as shown in Equation 7.

$\begin{matrix}{\begin{matrix}{\begin{bmatrix}\hat{s_{0}} \\s_{1}^{*}\end{bmatrix} = {H^{+}\begin{bmatrix}y^{1} \\y^{2*}\end{bmatrix}}} \\{= {{\left( {H^{H}H} \right)^{- 1}H^{H}{H\begin{bmatrix}s_{0} \\s_{1}^{*}\end{bmatrix}}} + {\left( {H^{H}H} \right)^{- 1}{H^{H}\begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}}}} \\{= {\begin{bmatrix}s_{0} \\s_{1}^{*}\end{bmatrix} + {\left( {H^{H}H} \right)^{- 1}{H^{H}\begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}}}}\end{matrix}\quad} & {{Equation}\mspace{14mu} 7}\end{matrix}$

In Equation 7, H⁺ denotes a pseudo inverse of H and may be calculated asH⁺=(H^(H)H)⁻¹H^(H) through a Hamiltonian matrix.

However, in an embodiment illustrated in FIG. 1, data symbols arenon-sequentially transmitted in no particular order, so thatimplementation cannot be directly performed in a Radio Frequency (RF)band. Further, since a complex conjugate operation of the data symbolcannot be implemented by an RF circuit, an embodiment illustrated inFIG. 1 always needs two transmitters.

Since two transmitters are used, the hardware configuration is complexand price, power consumption, and production cost also increase.Further, since the two transmitters should be synchronized, there is adisadvantage in that an additional clock distribution circuit is needed.If only one transmitter is used even though transmission diversity isimplemented, transmission diversity can be used even in variousapplication fields that could not use transmission diversity due to alow power problem.

Hereinafter, the disclosure discloses a method and an apparatus forimplementing transmission diversity using a single receiver in order tosolve the problem.

FIG. 2 is a block diagram of a communication system according to anembodiment of the disclosure.

Two transmission antennas (ANT1 and ANT2) and one receiver antenna(ANT3) illustrated in FIG. 2 are only an example, but the number ofantennas is not limited thereto and may vary.

Referring to FIG. 2, the communication system may include a transmitter210 and a receiver 230.

The transmitter 210 may have a plurality of antennas (ANT1 and ANT2) andmay implement transmission diversity using data symbols transmittedthrough the plurality of antennas (ANT1 and ANT2). A data symboltransmitted through the first antenna (ANT1) of the transmitter 210 maybe received through a third antenna (ANT3) of the receiver 230 accordingto a first channel characteristic (h₀), and a data symbol transmittedthrough the second antenna (ANT2) of the transmitter 210 may be receivedthrough the third antenna (ANT3) of the receiver 230 according to asecond channel characteristic (h₁). The receiver 230 may reconstruct theoriginal data symbol transmitted from the transmitter 210 through datasymbols received by the third antenna (ANT3) through various paths.

According to an embodiment, the plurality of antennas (ANT1 and ANT2) ofthe transmitter 210 may be implemented as Single Resonator Multiple Mode(SRMM) antennas. The SRMM antenna refers to an antenna in which twoantennas having multiple modes are integrated in one antenna structure.Through the use of the SRMM antenna, a problem of increasing the antennamay be solved.

According to an embodiment, the transmitter 210 and the receiver 230 maybe a device for transmitting data and a device for receiving data on thebasis of a downlink (DL) but are not limited thereto.

FIG. 3 is a block diagram of a communication system according to anembodiment of the disclosure.

Referring to FIG. 3, the transmitter 210 may include a data source 211,a processor 213, a phase adjustment coupler 215, and a plurality ofantennas (ANT1 and ANT2).

The data source 211 is a node or a network providing data and may be,for example, a node or a network supplying a baseband signal such as acore network of a base station, a backhaul, or the base station itself.

The processor 213 may perform various operation processing for thebaseband signal received from the data source 211. The processor 213 mayperform various signal processing such as repetitive generation of thebaseband signal received from the data source 211 and a complexconjugate operation for the received baseband signal. The processor 213may generate an RF signal in the form of a data symbol according to theresult of signal processing. According to an embodiment, the processor213 may be variously referred to as a baseband processor, and a separatecontroller (not shown) or processor (not shown) for controlling theoverall operation of the transmitter 210 may be provided according tooccasions.

The processor 213 may generate a switching signal (SW) for switching aswitch circuit 215 a within the phase adjustment coupler 215. A detailedoperation of the switch circuit 215 a according to the switching signal(SW) will be described below with reference to FIG. 4.

The phase adjustment coupler 215 may couple data symbols transmittedfrom the processor 213 and adjust and output phases of the coupled datasymbols.

The phase adjustment coupler 215 may include the switch circuit 215 aand a coupler circuit 215 b.

FIG. 4 illustrates a phase adjustment coupler according to an embodimentof the disclosure.

Referring to FIG. 4, the switch circuit 215 a may switch a signal pathof data symbols (for example, s₀, s*₀, s₁, and s*₁) transmitted from theprocessor 213.

The switch circuit 215 a may switch a signal path between a firstswitching node (SN1) and a second switching node (SN2) according to aswitching signal (SW) transmitted from the processor 213.

According to an embodiment, the switch circuit 215 a may alternatelyswitch the signal path between the first switching node (SN1) and thesecond switching node (SN2) in successive time slots.

The coupler circuit 215 b may include a plurality of input terminals(CI1 and CI2) and a plurality of output terminals (CO1 and CO2).

According to an embodiment, when the signal path is determined as thefirst switching node (SN1) by the switch circuit 215 a, the data symbol(for example, S0) transmitted from the processor 213 may be input intothe first input terminal (CI1) of the coupler circuit 215 b.

According to an embodiment, when the signal path is determined as thesecond switching node (SN2) by the switch circuit 215 a, the data symbol(for example, S0*) transmitted from the processor 213 may be input intothe second input terminal (CI2) of the coupler circuit 215 b.

According to an embodiment, the data symbol input into one of theplurality of input terminals (CI1 and CI2) of the coupler circuit 215 bmay be coupled via different signal paths in the coupler circuit 215 band then each of the coupled data symbols may be output to each of theplurality of output terminals (CO1 and CO2) of the coupler circuit 134.

According to an embodiment, the data symbol (for example, s₀) input intothe first input terminal (CI1) of the coupler circuit 215 b may becoupled to be data symbols (for example, s₀ and s₀) having the samephase as the input data symbol (for example, s₀) and output to theplurality of output terminals (CO1 and CO2), respectively.

According to an embodiment, the data symbol (for example, s*₀) inputinto the second input terminal (CI2) of the coupler circuit 215 b may becoupled to be the data symbol (for example, s*₀) having the same phaseas the input data symbol (for example, s*₀) and a data symbol (forexample, −s*₀) having only a phase difference of 180 degrees and outputto the plurality of output terminals (CO1 and CO2), respectively.

According to an embodiment, the coupler circuit 215 b may be implementedas a 180-degree hybrid coupler, in which case the first input terminal(CI1) may be a sum terminal for coupling the input signal to be twosignals having the same phase and outputting the two signals and thesecond input terminal (CI2) may be a difference terminal for couplingthe input signal to be two signals having a phase difference of 180degrees therebetween and outputting the two signals.

FIG. 5 is a flowchart illustrating the operation of a transmitter towhich transmission diversity is applied according to an embodiment ofthe disclosure.

Referring to FIG. 5, operations 501, 503, 505, 507, 509 and 511 of FIG.5 may be performed by the transmitter 210 of the communication systemaccording to an embodiment.

In operation 501, the transmitter 210 may receive a baseband signal fromthe data source 211 and generate a first data symbol.

According to an embodiment, the transmitter 210 may include theprocessor 213 and perform various signal processing such as repetitivegeneration of the baseband signal received from the data source 211 andthe complex conjugate operation for the received baseband signal by theprocessor 213.

In operation 503, the transmitter 210 may generate a second data symbolhaving the same phase as the first data symbol.

According to an embodiment, when the first data symbol is s₀, the firstdata symbol (for example, s₀) may be input into the first input terminal(CI1) of the coupler circuit 215 b through the first switching node(SN1) according to the switching operation of the switch circuit 215 ain a first time slot, coupled to be second data symbols (for example,s₀) having the same phase as the first data symbol (for example, S0) viaa signal path in the coupler circuit 215 b, and output to the pluralityof output terminals (CO1 and CO2).

According to an embodiment, the output first data symbol and second datasymbol (for example, s₀) may be transmitted to the outside in parallelthrough the first transmission antenna and the second transmissionantenna (ANT1 and ANT2), respectively.

In operation 505, the transmitter 210 may perform the complex conjugateoperation for the first data symbol (for example, S0) transmitted inoperation 501 and generate a first complex conjugate symbol (forexample, s*₀).

According to an embodiment, operation 505 may be performed by theprocessor 213 of the transmitter 210, and the first complex conjugatesymbol (for example, s*₀) may be generated by performing a complexconjugate operation after temporarily storing the first data symbol (forexample, s₀).

According to operation 507, the transmitter 210 may generate a secondcomplex conjugate symbol (for example, −s*₀) having a phase differenceof 180 degrees from the first complex conjugate symbol (s*₀).

According to an embodiment, when the first complex conjugate symbol isS0*, the first complex conjugate symbol (for example, s*₀) may be inputinto the second input terminal (CI2) of the coupler circuit 134 throughthe second switching node (SN2) according to the switching operation ofthe switching circuit 132 in a second time slot, coupled to be thesecond data symbol (for example, −s*₀) having only a phase difference of180 degrees from the first complex conjugate symbol (for example, s*₀)via a signal path in the coupler circuit 134, and output to theplurality of output terminals (CO1 and CO2), respectively.

In operation 509, the output first data symbol (for example, s₀) andsecond data symbol (for example, s₀) may be transmitted to the outsidein parallel through the first transmission antenna and the secondtransmission antenna (ANT1 and ANT2), respectively, in the first timeslot.

In operation 511, the output first complex conjugate symbol (forexample, s*₀*) and second complex conjugate symbol (for example, −s*₀)may be transmitted to the outside in parallel through the firsttransmission antenna and the second transmission antenna (ANT1 andANT2), respectively, in the second time slot.

According to an embodiment, the first time slot and the second time slotare temporally continuous time slots.

According to an embodiment, first transmission data symbols and secondtransmission data symbols may be transmitted after application oftime-space block encoding. Accordingly, it is possible to improvereliability of data transmission through the use of data of variousversions received after transmission of several copies of a data streamthrough a plurality of antennas.

FIG. 6 is a flowchart illustrating the operation of a receiver to whichtransmission diversity is applied according to an embodiment of thedisclosure.

Referring to FIG. 6, operations 601, 603 and 605 of FIG. 6 may beperformed by the receiver 230 of the communication system according toan embodiment.

In operation 601, the receiver 230 may receive a first data symbol and asecond data symbol having the same phase as the first data symbol in afirst time slot.

According to an embodiment, the receiver 230 may receive data symbols(for example, S0 and S0) having the same phase as each other in thefirst time slot.

In operation 603, the receiver 230 may receive a first complex conjugatesymbol and a second complex conjugate symbol having only a phasedifference of 180 degrees from the first complex conjugate symbol.

According to an embodiment, the first complex conjugate symbol may begenerated by performing a complex conjugate operation for the first datasymbol.

According to an embodiment, the receiver 230 may receive the firstcomplex conjugate symbol and the second complex conjugate symbol (forexample, s*₀and −s*₀) having only a phase difference of 180 degrees fromeach other in a second time slot, and the first complex conjugate symbol(for example, s*₀) among the first complex conjugate symbol and thesecond complex conjugate symbol (for example, s*₀and −s₀) may have acomplex conjugate relation with the first data symbol (for example, s₀).

In operation 605, the receiver 230 may reconstruct the data symbol towhich transmission diversity is applied on the basis of the first datasymbol and the second data symbol (for example, s₀ and s₀) and the firstcomplex conjugate symbol and the second complex conjugate symbol (forexample, s*₀and −s*₀).

According to an embodiment, operation 605 may be performed by aprocessor (not shown) included in the receiver 100 or a baseband signalprocessor (not shown).

According to an embodiment, a process in which the receiver 230reconstruct the data symbols to which transmission diversity is appliedon the basis of the first data symbol and the second data symbol (forexample, s₀ and s₀) and the first complex conjugate symbol and thesecond complex conjugate symbol (for example, S0*and −S0*) may beperformed as follows.

According to an embodiment, a reception signal y^(k) received by thereceiver 230 may be indicated in the form as shown in Equation 8 andEquation 9.y ¹ =h ₀ s ₀ +h ₁ s ₀ +n ¹  Equation 8y ² =h ₀(−s* ₀)+h ₁ s* ₀ +n ²  Equation 9

(y^(k) denotes a reception signal in a k^(th) time slot, h_(n) denotes achannel characteristic of an nth channel, s₀, s*₀, and −s*₀denotetransmission data symbols, and n^(k) denotes Additive White GaussianNoise (AWGN) in a k^(th) time slot)

At this time, Equation 10 may be derived after a complex conjugate ofEquation 9 is obtained and expressed as a matrix.

$\begin{matrix}{\begin{bmatrix}y^{1} \\y^{2*}\end{bmatrix} = {{\begin{bmatrix}h_{o} & {- h_{1}} \\h_{1}^{*} & {- h_{o}^{*}}\end{bmatrix}\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix}} + \begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}} & {{Equation}\mspace{14mu} 10}\end{matrix}$

$H_{2 \times 1} = \begin{bmatrix}h_{0} & h_{1} \\h_{1}^{*} & {- h_{0}^{*}}\end{bmatrix}$may be defined, and when Equation 10 is solved for

$\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix},$a transmitted data symbol may be estimated as shown in Equation 11. H⁺denotes a pseudo inverse of a matrix H.

$\begin{matrix}{\begin{matrix}{\begin{bmatrix}\hat{s_{0}} \\s_{0}\end{bmatrix} = {H_{2 \times 1}^{+}\begin{bmatrix}y^{1} \\y^{2*}\end{bmatrix}}} \\{= {{\left( {H_{2 \times 1}^{H}H_{2 \times 1}} \right)^{- 1}H_{2 \times 1}^{H}{H_{2 \times 1}\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix}}} +}} \\{\left( {H_{2 \times 1}^{H}H_{2 \times 1}} \right)^{- 1}{H_{2 \times 1}^{H}\begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}} \\{= {\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix} + {\left( {H_{2 \times 1}^{H}H_{2 \times 1}} \right)^{- 1}{H_{2 \times 1}^{H}\begin{bmatrix}n^{1} \\n^{2*}\end{bmatrix}}}}}\end{matrix}\quad} & {{Equation}\mspace{14mu} 11}\end{matrix}$

In Equation 11, only a symbol is repeated in an Alamouti code, andEquation 11 may be processed using at least some of the receiverstructure in which an existing Alamouti transmission diversity signalcan be processed according to an embodiment.

According to an embodiment, when two reception antennas are used, areception signal may be expressed as Equation 12 and Equation 13. y_(i)^(k) denotes a signal of an i^(th) reception antenna in a k(k=1, 2)^(th)time slot. h_(j) denotes a channel coefficient from a j^(th)transmission antenna to an i^(th) reception antenna, and n_(i) ^(k)denotes additive Gaussian white noise in a k^(th) time slot of a signalreceived by an i^(th) reception antenna.y ₀ ¹ =h ₀₀ s ₀ +h ₀₁ s ₀ +n ₀ ¹y ₁ ¹ =h ₀₀ s ₀ +h ₁₁ s ₀ +n ₁ ¹  Equation 12y ₀ ² =h ₀₀(−s* ₀)+h ₀₁ s* ₀ +n ₀ ²y ₁ ² =−h ₁₀(s* ₀)+h ₁₁ s* ₀ +n ₁ ²  Equation 13

Equation 7 may be derived by performing a complex conjugate operationfor both sides of Equation 14 and summarizing it again.

$\begin{matrix}{\begin{bmatrix}y_{0}^{1} \\y_{1}^{1} \\y_{0}^{2^{*}} \\y_{1}^{2^{*}}\end{bmatrix} = {{\begin{bmatrix}h_{00} & h_{01} \\h_{10} & h_{11} \\h_{01}^{*} & {- h_{00}^{*}} \\h_{11}^{*} & {- h_{10}}\end{bmatrix}\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix}} + \begin{bmatrix}n_{0}^{1} \\n_{1}^{1} \\n_{0}^{2^{*}} \\n_{1}^{2^{*}}\end{bmatrix}}} & {{Equation}\mspace{14mu} 14}\end{matrix}$

When

$H_{2 \times 2} = \begin{bmatrix}h_{00} & h_{01} \\h_{10} & h_{11} \\h_{01}^{*} & {- h_{00}^{*}} \\h_{11}^{*} & {- h_{10}}\end{bmatrix}$is defined and Equation 14 is solved using a pseudo inverse matrix for

$\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix},$a symbol may be estimated as shown in Equation 15 below.

$\begin{matrix}{\begin{matrix}{\begin{bmatrix} \\s_{0}\end{bmatrix} = {H_{2 \times 2}^{+}\begin{bmatrix}y_{0}^{1} \\y_{1}^{1} \\y_{0}^{2^{*}} \\y_{1}^{2^{*}}\end{bmatrix}}} \\{= {{\left( {H_{2 \times 2}^{H}H_{2 \times 2}} \right)^{- 1}H_{2 \times 2}^{H}{H_{2 \times 2}\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix}}} +}} \\{\left( {H_{2 \times 2}^{H}H_{2 \times 2}} \right)^{- 1}{H_{2 \times 2}^{H}\begin{bmatrix}n_{0}^{1} \\n_{1}^{1} \\n_{0}^{2^{*}} \\n_{1}^{2^{*}}\end{bmatrix}}} \\{= {\begin{bmatrix}s_{0} \\s_{0}\end{bmatrix} + {\left( {H_{2 \times 2}^{H}H_{2 \times 2}} \right)^{- 1}{H_{2 \times 2}^{H}\begin{bmatrix}n_{0}^{1} \\n_{1}^{1} \\n_{0}^{2^{*}} \\n_{1}^{2^{*}}\end{bmatrix}}}}}\end{matrix}\quad} & {{Equation}\mspace{14mu} 15}\end{matrix}$

FIG. 7 is a graph illustrating comparison of a Bit Error Rate (BER) whentransmission diversity is applied according to an embodiment of thedisclosure.

Referring to FIG. 7, when transmission diversity is applied in acommunication system in which two transmission antennas and onereception antenna are implemented according to an embodiment, it may benoted that the BER is excellent such that a theoretical value of theexisting Alamouti transmission diversity and a simulation result match(nTx=2, nRx=1, Alamouti with 180° Hybrid).

FIG. 8 is a graph illustrating comparison of a Bit Error Rate (BER) whentransmission diversity is applied according to an embodiment of thedisclosure.

Referring to FIG. 8, when transmission diversity is applied in acommunication system in which two transmission antennas and onereception antenna are implemented according to an embodiment, it may benoted that the BER is excellent such that a theoretical value of theexisting Alamouti transmission diversity and a simulation result match(nTx=2, nRx=1, Alamouti with 180° Hybrid).

FIG. 9 is a graph illustrating a reflection loss of a phase adjustmentcoupler according to an embodiment of the disclosure.

FIG. 10 is a graph illustrating an insertion loss and an isolationdegree of a phase adjustment coupler according to an embodiment of thedisclosure.

FIG. 11 is a graph illustrating a phase difference between outputsignals of a phase adjustment coupler according to an embodiment of thedisclosure.

Referring to FIGS. 9 to 11, operation characteristics in 2.4 gigahertz(GHz) in the case of a phase adjustment coupler (130B of FIG. 5)according to an embodiment are illustrated.

Referring to FIG. 9, an input reflection coefficient has acharacteristic equal to or lower than −15 decibels (dB) at allterminals. Referring to FIG. 10, it may be noted that an insertion lossis −3 dB according to a hybrid operation and an isolation degree betweenantennas is measured as −25 dB. Referring to FIG. 11, a phase differenceof exactly 180 degrees may be identified in a band of 2.4 GHz.

FIG. 12 illustrates actual implementation of a coupler circuit accordingto an embodiment of the disclosure.

Referring to FIG. 12, in the case of a frequency band having a centerfrequency of 920 megahertz (MHz) according to an embodiment, the phaseadjustment coupler 215 may be implemented as illustrated in FIG. 12. Atthis time, the phase adjustment coupler 215 may include a switch circuit1201 and a coupler circuit 1203 in the form as illustrated in FIG. 4.

FIG. 13 illustrates actual implementation of a coupler circuit accordingto an embodiment of the disclosure.

Referring to FIG. 13, in the case of a frequency band having a centerfrequency of 2.5 GHz according to an embodiment, the phase adjustmentcoupler 215 may be implemented as illustrated in FIG. 13. At this time,the phase adjustment coupler 215 may include a switch circuit 1301 and acoupler circuit 1303 in the form as illustrated in FIG. 12.

A method of operating a transmitter for transmission diversity in awireless communication system according to an embodiment may include aprocess of generating a first data symbol by receiving a baseband signalfrom a data source, a process of generating a second data symbol havingan equal phase to the first data symbol, a process of generating a firstcomplex conjugate symbol by performing a complex conjugate operation forthe first data symbol, a process of generating a second complexconjugate symbol having a phase difference of 180 degrees from the firstcomplex conjugate symbol, a process of transmitting the first datasymbol through a first transmission antenna and transmitting the seconddata symbol through a second transmission antenna in a first time slot,and a process of transmitting the first complex conjugate symbol throughthe first transmission antenna and transmitting the second complexconjugate symbol through the second transmission antenna in a secondtime slot.

According to an embodiment, the first time slot and the second time slotmay be continuous time slots.

According to an embodiment, the first data symbol, the second datasymbol, the first complex conjugate symbol, and the second complexconjugate symbol may be transmitted after application of a time-spaceblock encoding.

According to an embodiment, the first data symbol and the first complexconjugate symbol may be processed or generated by a single processor forprocessing the baseband signal.

According to an embodiment, the first transmission antenna and thesecond transmission antenna may be implemented as Single ResonatorMultiple Mode (SRMM) antennas.

According to an embodiment, the second data symbol may be generated viaa first signal path, and the first signal path may be a signal pathpassing through a sum terminal of a coupler circuit.

According to an embodiment, the second complex conjugate symbol may begenerated via a second signal path, and the second signal path may be asignal path passing through a difference terminal of a coupler circuit.

According to an embodiment, the method may further include a process ofstoring the first data symbol and a process of performing a complexconjugate operation for the stored first data symbol.

A transmitter for transmission diversity in a wireless communicationsystem may include: a processor; a phase adjustment coupler connected tothe processor to operate and including a switch circuit and a couplercircuit; and a first transmission antenna and a second transmissionantenna connected to the phase adjustment coupler to operate, whereinthe processor is configured to generate a first data symbol by receivinga baseband signal from a data source and generate a first complexconjugate symbol by performing a complex conjugate operation for thefirst data symbol, the phase adjustment coupler is configured togenerate a second data symbol having an equal phase to the first datasymbol and generate a second complex conjugate symbol having a phasedifference of 180 degrees from the first complex conjugate symbol, thefirst data symbol is transmitted through the first transmission antennaand the second data symbol is transmitted through the secondtransmission antenna in a first time slot, and the first complexconjugate symbol is transmitted through the first antenna and the secondcomplex conjugate symbol is transmitted through the second antenna in asecond time slot.

According to an embodiment, the first time slot and the second time slotmay be continuous time slots.

According to an embodiment, the first data symbol, the second datasymbol, the first complex conjugate symbol, and the second complexconjugate symbol may be transmitted after application of a time-spaceblock encoding.

According to an embodiment, the first data symbol and the first complexconjugate symbol may be processed or generated by a single processor forprocessing the baseband signal.

According to an embodiment, the first transmission antenna and thesecond transmission antenna may be implemented as Single ResonatorMultiple Mode (SRMM) antennas.

According to an embodiment, the second data symbol may be generated viaa first signal path, and the first signal path may be a signal pathpassing through a first switching node of the switch circuit and a sumterminal of the coupler circuit.

According to an embodiment, the second complex conjugate symbol may begenerated via a second signal path, and the second signal path may be asignal path passing through a second switching node of the switchcircuit and a difference terminal of the coupler circuit.

According to an embodiment, the processor may be configured to store thefirst data symbol and perform a complex conjugate operation for thestored first data symbol.

According to an embodiment, the phase adjustment coupler may beconfigured to couple a data symbol transmitted from the processor andadjust and output phases of the coupled data symbols.

A method of operating a receiver for transmission diversity in awireless communication system according to an embodiment may include aprocess of receiving a first data symbol and a second data symbol in afirst time slot, a process of receiving a first complex conjugate symboland a second complex conjugate symbol in a second time slot, and aprocess of reconstructing a data symbol to which transmission diversityis applied, based on the first data symbol, the second data symbol, thefirst complex conjugate symbol, and the second complex conjugate symbol,wherein the first data symbol and the second data symbol have an equalphase, the first complex conjugate symbol and the second complexconjugate symbol have a phase difference of 180 degrees, and the firstcomplex conjugate symbol is generated by performing a complex conjugateoperation for the first data symbol.

According to an embodiment, the first time slot and the second time slotmay be continuous time slots.

According to an embodiment, the first data symbol, the second datasymbol, the first complex conjugate symbol, and the second complexconjugate symbol may be transmitted after application of a time-spaceblock encoding.

It should be appreciated that various embodiments of the disclosure andthe terms used therein are not intended to limit the technologicalfeatures set forth herein to particular embodiments and include variouschanges, equivalents, or alternatives for a corresponding embodiment.With regard to the description of the drawings, similar referencenumerals may be used to designate similar or relevant elements. It is tobe understood that a singular form of a noun corresponding to an itemmay include one or more of the things, unless the relevant contextclearly indicates otherwise. As used herein, each of such phrases as “Aor B,” “at least one of A and B,” “at least one of A or B,” “A, B, orC,” “at least one of A, B, and C,” and “at least one of A, B, or C,” mayinclude all possible combinations of the items enumerated together in acorresponding one of the phrases. As used herein, such terms as “afirst”, “a second”, “the first”, and “the second” may be used to simplydistinguish a corresponding element from another, and does not limit theelements in other aspect (e.g., importance or order). It is to beunderstood that if an element (e.g., a first element) is referred to,with or without the term “operatively” or “communicatively”, as “coupledwith,” “coupled to,” “connected with,” or “connected to” another element(e.g., a second element), it means that the element may be coupled withthe other element directly (e.g., wiredly), wirelessly, or via a thirdelement.

As used herein, the term “module” may include a unit implemented inhardware, software, or firmware, and may be interchangeably used withother terms, for example, “logic,” “logic block,” “component,” or“circuit”. The “module” may be a minimum unit of a single integratedcomponent adapted to perform one or more functions, or a part thereof.For example, according to an embodiment, the “module” may be implementedin the form of an application-specific integrated circuit (ASIC).

Various embodiments as set forth herein may be implemented as software(e.g., the program 140) including one or more instructions that arestored in a storage medium (e.g., internal memory 136 or external memory138) that is readable by a machine (e.g., the electronic device 101).For example, a processor (e.g., the processor 120) of the machine (e.g.,the electronic device 101) may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. This allows the machine to be operated to perform at leastone function according to the at least one instruction invoked. The oneor more instructions may include a code generated by a complier or acode executable by an interpreter. The machine-readable storage mediummay be provided in the form of a non-transitory storage medium. Wherein,the term “non-transitory” simply means that the storage medium is atangible device, and does not include a signal (e.g., an electromagneticwave), but this term does not differentiate between where data issemi-permanently stored in the storage medium and where the data istemporarily stored in the storage medium.

According to an embodiment, a method according to various embodiments ofthe disclosure may be included and provided in a computer programproduct. The computer program product may be traded as a product betweena seller and a buyer. The computer program product may be distributed inthe form of a machine-readable storage medium (e.g., compact disc readonly memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded)online via an application store (e.g., Play Store), or between two userdevices (e.g., smart phones) directly. If distributed online, at leastpart of the computer program product may be temporarily generated or atleast temporarily stored in the machine-readable storage medium, such asmemory of the manufacturer's server, a server of the application store,or a relay server.

According to various embodiments, each element (e.g., a module or aprogram) of the above-described elements may include a single entity ormultiple entities. According to various embodiments, one or more of theabove-described elements may be omitted, or one or more other elementsmay be added. Alternatively or additionally, a plurality of elements(e.g., modules or programs) may be integrated into a single element. Insuch a case, according to various embodiments, the integrated elementmay still perform one or more functions of each of the plurality ofelements in the same or similar manner as they are performed by acorresponding one of the plurality of elements before the integration.According to various embodiments, operations performed by the module,the program, or another element may be carried out sequentially, inparallel, repeatedly, or heuristically, or one or more of the operationsmay be executed in a different order or omitted, or one or more otheroperations may be added.

Methods disclosed in the claims and/or methods according to variousembodiments described in the specification of the disclosure may beimplemented by hardware, software, or a combination of hardware andsoftware.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program may includeinstructions that cause the electronic device to perform the methodsaccording to various embodiments of the disclosure as defined by theappended claims and/or disclosed herein.

The programs (software modules or software) may be stored innon-volatile memories including a random access memory and a flashmemory, a read only memory (ROM), an electrically erasable programmableread only memory (EEPROM), a magnetic disc storage device, a compactdisc-ROM (CD-ROM), digital versatile discs (DVDs), or other type opticalstorage devices, or a magnetic cassette. Alternatively, any combinationof some or all of them may form a memory in which the program is stored.Further, a plurality of such memories may be included in the electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich may access the electronic device through communication networkssuch as the Internet, Intranet, Local Area Network (LAN), Wide LAN(WLAN), and Storage Area Network (SAN) or a combination thereof. Such astorage device may access the electronic device via an external port.Further, a separate storage device on the communication network mayaccess a portable electronic device.

In the above-described detailed embodiments of the disclosure, anelement included in the disclosure is expressed in the singular or theplural according to presented detailed embodiments. However, thesingular form or plural form is selected appropriately to the presentedsituation for the convenience of description, and the disclosure is notlimited by elements expressed in the singular or the plural. Therefore,either an element expressed in the plural may also include a singleelement or an element expressed in the singular may also includemultiple elements.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a transmitter fortransmission diversity in a wireless communication system, the methodcomprising: generating, by a processor, a first data symbol by receivinga baseband signal from a data source; generating, by a phase adjustmentcoupler operably connected to the processor and the phase adjustmentcoupler including a switch circuit and a coupler circuit, a second datasymbol having an equal phase to the first data symbol; generating, bythe processor, a first complex conjugate symbol by performing a complexconjugate operation for the first data symbol; generating, by the phaseadjustment coupler, a second complex conjugate symbol having a phasedifference of 180 degrees from the first complex conjugate symbol;transmitting, by a first transmission antenna operably connected to thephase adjustment coupler, the first data symbol through a firsttransmission antenna and transmitting the second data symbol through asecond transmission antenna, in a first time slot; and transmitting, bya second transmission antenna operably connected to the phase adjustmentcoupler, the first complex conjugate symbol through the firsttransmission antenna and transmitting the second complex conjugatesymbol through the second transmission antenna, in a second time slot.2. The method of claim 1, wherein the first time slot and the secondtime slot are continuous time slots.
 3. The method of claim 1, whereinthe first data symbol, the second data symbol, the first complexconjugate symbol, and the second complex conjugate symbol aretransmitted after application of a time-space block encoding.
 4. Themethod of claim 1, wherein the first data symbol and the first complexconjugate symbol are processed or generated by a single processor forprocessing the baseband signal.
 5. The method of claim 1, wherein thefirst transmission antenna and the second transmission antenna areimplemented as single resonator multiple mode (SRMM) antennas.
 6. Themethod of claim 1, wherein the second data symbol is generated via afirst signal path, and wherein the first signal path is a signal pathpassing through a sum terminal of a coupler circuit.
 7. The method ofclaim 1, wherein the second complex conjugate symbol is generated via asecond signal path, and wherein the second signal path is a signal pathpassing through a difference terminal of a coupler circuit.
 8. Themethod of claim 1, further comprising: storing the first data symbol;and performing the complex conjugate operation for the stored first datasymbol.
 9. A transmitter for transmission diversity in a wirelesscommunication system, the transmitter comprising: a processor; a phaseadjustment coupler connected to the processor to operate and comprisinga switch circuit and a coupler circuit; and a first transmission antennaand a second transmission antenna connected to the phase adjustmentcoupler to operate, wherein the processor is configured to generate afirst data symbol by receiving a baseband signal from a data source andgenerate a first complex conjugate symbol by performing a complexconjugate operation for the first data symbol, wherein the phaseadjustment coupler is configured to generate a second data symbol havingan equal phase to the first data symbol and generate a second complexconjugate symbol having a phase difference of 180 degrees from the firstcomplex conjugate symbol, wherein the first data symbol is transmittedthrough the first transmission antenna and the second data symbol istransmitted through the second transmission antenna in a first timeslot, and wherein the first complex conjugate symbol is transmittedthrough the first transmission antenna and the second complex conjugatesymbol is transmitted through the second transmission antenna in asecond time slot.
 10. The transmitter of claim 9, wherein the first timeslot and the second time slot are continuous time slots.
 11. Thetransmitter of claim 9, wherein the first data symbol, the second datasymbol, the first complex conjugate symbol, and the second complexconjugate symbol are transmitted after application of a time-space blockencoding.
 12. The transmitter of claim 9, wherein the first data symboland the first complex conjugate symbol are processed or generated by asingle processor for processing the baseband signal.
 13. The transmitterof claim 9, wherein the first transmission antenna and the secondtransmission antenna are implemented as single resonator multiple mode(SRMM) antennas.
 14. The transmitter of claim 9, wherein the second datasymbol is generated via a first signal path, and wherein the firstsignal path is a signal path passing through a first switching node ofthe switch circuit and a sum terminal of the coupler circuit.
 15. Thetransmitter of claim 9, wherein the second complex conjugate symbol isgenerated via a second signal path, and wherein the second signal pathis a signal path passing through a second switching node of the switchcircuit and a difference terminal of the coupler circuit.
 16. Thetransmitter of claim 9, wherein the processor is further configured to:store the first data symbol; and perform the complex conjugate operationfor the stored first data symbol.
 17. The transmitter of claim 9,wherein the phase adjustment coupler is further configured to: coupledata symbols transmitted from the processor; and adjust and outputphases of the coupled data symbols.